Heat Pump Circuit for Vehicles

ABSTRACT

A heat pump circuit for heating a vehicle passenger compartment and/or a vehicle component is provided. The heat pump circuit includes an electrical heating device arranged to heat a refrigerant flowing through the heat pump circuit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International Application No. PCT/EP2012/056172, filed Apr. 4, 2012, which claims priority under 35 U.S.C. §119 from German Patent Application No. DE 10 2011 076 507.7, filed May 26, 2011, the entire disclosures of which are expressly incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a heat pump circuit for heating a passenger cabin of a vehicle, the heat pump circuit including an electric heater.

A laundry drying machine having a heat pump circuit is known from European patent document no. EP 1 983 095 A2, in which a heater is arranged therein. The heat pump circuit has—when viewed in the direction of flow of the refrigerant medium flowing through the heat pump circuit—a compressor, a condenser, an auxiliary heat exchanger, an evaporator, and a heater. The heater is arranged between an output of the evaporator and a suction intake of the compressor, in series in the heat pump circuit. The heater is included for the purpose of raising the temperature in the heat pump circuit at the start of the drying process, and/or for the purpose of maintaining the refrigerant medium in the gaseous phase during operating modes in which there is a risk of the compressor taking in liquid refrigerant medium.

The problem addressed by the invention is that of creating a heat pump circuit which is also suitable for other technology fields.

The invention proceeds from the concept of heating a vehicle—meaning the passenger cabin of a vehicle, and/or components of a vehicle which must be kept at temperature, such as a high-voltage storage device or the like, for example—by a heat pump arrangement. It is known that the degree of efficiency of a heat pump arrangement depends on the temperature of the surrounding air used as the heat source. At low temperatures, such as in winter for example, the degree of efficiency and/or the coefficient of performance of a conventional heat pump system is so minimal that it is relatively uneconomical to use a heat pump system.

A central concept of the invention is the idea of equipping a vehicle with a heat pump circuit which, in contrast to conventional heat pump circuits, has an additional electrical heater device, by which it is possible to supply heat to the refrigerant medium flowing through the heat pump circuit. By “preheating” the refrigerant medium, it is thereby possible to reach a sufficiently high degree of efficiency and/or a sufficiently high coefficient of performance, even at low surrounding air temperatures, to make reasonable the use of the invention in vehicles.

According to one implementation of the invention, the heat pump circuit has two refrigerant medium branches through which refrigerant medium flows, particularly a first refrigerant medium branch and a second refrigerant medium branch which is arranged parallel thereto and/or “connected” in parallel thereto.

A heat pump circuit according to the invention has a refrigerant medium compressor with a pressure outlet having a flow connection to an input of a first heat exchanger. The first heat exchanger is included for the purpose of releasing heat from the refrigerant medium to the passenger cabin and/or to the vehicle components being heated (such as a high-voltage storage device, for example).

Viewed in the direction in which the refrigerant medium flows, a “branching point” is included in the fluid system of the heat pump circuit after the first heat exchanger. At this point, the heat pump circuit branches into the two refrigerant medium branches mentioned above.

A second heat exchanger can be configured in a first branch of the two refrigerant medium branches. During heat pump operation, the second heat exchanger functions as an evaporator. Heat contained in the surrounding air and/or in the airstream is released via the second heat exchanger to the cooler refrigerant medium flowing through the second heat exchanger.

According to one implementation of the invention, the electrical heater device is arranged in the second refrigerant medium branch, the same arranged parallel to the first refrigerant medium branch, which is a very key difference with respect to the document EP 1 983 095 A2 mentioned above. By way of example, the second refrigerant medium branch can have a refrigerant medium tube through which refrigerant medium flows, or a component embodied in another manner, through which refrigerant medium flows, wherein said tube or component can be heated by the electrical heater device.

A shut-off device can be functionally assigned to each of the two refrigerant medium branches, wherein the refrigerant medium branch can be shut off via the respective shut-off device. At very low outside temperatures, when it is not possible to produce a significant heat input via the second heat exchanger, the first refrigerant medium branch can be shut off via the assigned shut-off device, such that all of the circulating refrigerant medium flows through the second refrigerant medium branch.

As an alternative, refrigerant medium can also flow through both of the refrigerant medium branches in parallel.

In a further operating mode, the second refrigerant medium branch can be shut off via the assigned shut-off device, wherein the total heat input occurs via the second heat exchanger—meaning via the heat contained in the surrounding air.

At least one expansion element is arranged between an output of the first heat exchanger, on the one hand, and the second heat exchanger and the heater device on the other hand. An expansion element is preferably arranged in each of the two refrigerant medium branches. A first expansion element can be arranged in the first refrigerant medium branch before the second heat exchanger, and a second expansion element can be arranged in the second refrigerant medium branch before the heater device.

As an alternative thereto, the configuration can have only one single expansion element which is arranged before the “branching point” at which the heat pump circuit branches into the two refrigerant medium branches.

As already mentioned, the second heat exchanger is arranged in the vehicle in such a manner that air and/or the airstream flows around and/or through it. By way of example, an electric fan can be included which actively blows air through the second heat exchanger. In contrast thereto, the second refrigerant medium branch and/or the components thereof can be arranged in a protected position in the vehicle, particularly in the engine compartment of the vehicle, rather than having the airstream flow around or through it and/or them—or at least not directly.

By a heat pump circuit according to the invention, in comparison to the conventional heat pump circuits (with no heater device), with circuit components which are otherwise sized the same, it is possible to achieve a significant increase in performance. This enables an economical deployment in vehicles, and particularly even in the cold seasons—meaning at low surrounding air temperatures. The arrangement of the electrical heater device in a bypass to the second heat exchanger can be very simply implemented in terms of construction—for example as an electrically heated refrigerant medium tube.

The invention is also particularly suited for hybrid- or purely electric vehicles. In these applications, the heat pump arrangement can be used for heating high-voltage components, such as a high-voltage storage device or power electronics, for example. As such, high-voltage components which must be heated can be arranged at any point in the vehicle, and need not necessarily be arranged in the vehicle interior.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic illustration of an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWING

FIG. 1 shows a heat pump circuit 1 having a refrigerant medium compressor 2 which is connected to an input 4 of a first heat exchanger 5 via a liquid line 3. Refrigerant medium which is compressed by the refrigerant medium compressor 2 and accordingly heated flows through the first heat exchanger 5 and thereby releases heat to a passenger cabin of a vehicle which is not illustrated here in greater detail, or to a vehicle component (not illustrated), of the vehicle, being heated. This is symbolized by an arrow 6.

One output 7 of the first heat exchanger 5 is connected to a branching point 9 via a refrigerant medium conduit 8, wherein the heat pump circuit 1 branches at said branching point 9 into a first refrigerant medium branch 10 and a second refrigerant medium branch 11. The first refrigerant medium branch 10 has a first expansion element 12 in which the refrigerant medium arriving from the first heat exchanger 5 releases pressure and is cooled.

The cooled refrigerant medium coming from the first expansion element 12 flows through a second heat exchanger 13, which absorbs heat from the surrounding air. This is symbolized by arrow 14. The second heat exchanger 13 can be arranged in the vehicle in such a manner that the airstream flows directly around or through it. An output 15 of the second heat exchanger 13 has a flow connection to a suction connector of the refrigerant medium compressor 2, via a liquid line 16 and a collector 17.

The second refrigerant medium branch 11 is arranged parallel to the first refrigerant medium branch 10 and has—when viewed in the direction of flow of the refrigerant medium—a second expansion element 19, and a component 21 through which refrigerant medium flows, said component being able to be heated by an electric heater device 20. The component 21 can be a simple refrigerant medium tube through which refrigerant medium flows, or also a heat exchanger, by way of example.

As an alternative to the embodiment shown in FIG. 1, the configuration can also have only one single expansion element. This can be arranged upstream of the branching point 9, when viewed in the direction of refrigerant medium flow.

In addition, a shut-off device can be included in each of the two refrigerant medium branches 10, 11—for example in the region between the branching point 9 and the first and/or second expansion element 12, 19. As an alternative, the expansion elements 12, 19 can also be designed as expansion elements which can be shut off In this manner, three different operating states can be “run” in principle—namely:

-   -   a first operating state in which refrigerant medium flows         through the two refrigerant medium branches 10, 11 in parallel,     -   a second operating state in which the second refrigerant medium         branch 11 is shut off and the entire volume of refrigerant         medium flows through the first refrigerant medium branch 10,         which may be practical when the surrounding air temperature is         high, for example (seasonal transition and/or summer operation),     -   a third operating state in which the first refrigerant medium         branch 10 is shut off and the entire volume of refrigerant         medium flows through the second refrigerant medium branch 11,         which may be practical at low surrounding air temperatures         (winter operation), for example. In this case, the refrigerant         medium can be (pre-)heated via the electric heater device 20.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 

What is claimed is:
 1. A heat pump circuit for a vehicle, comprising: a vehicle; a circuit in the vehicle through which a heat pump is arranged to circulate a refrigerant medium provided for transferring heat to at least one of a passenger cabin of the vehicle and a vehicle component; and an electric heater device arranged to heat the refrigerant medium flowing through the heat pump circuit.
 2. The heat pump circuit according to claim 1, wherein the heat pump circuit includes a first refrigerant medium branch and a second refrigerant medium branch parallel to the first refrigerant medium branch.
 3. The heat pump circuit according to claim 2, wherein the heat pump is a refrigerant medium compressor, the heat pump circuit includes a first heat exchanger, the refrigerant medium compressor includes a pressure output connected to an input of the first heat exchanger, and the first heat exchanger is configured to directly or indirectly release heat from the refrigerant medium to the at least one of the passenger cabin and the vehicle component.
 4. The heat pump circuit according to claim 3, wherein a branching point is provided in the heat pump circuit downstream in a direction of flow of the refrigerant medium from the first heat exchanger and upstream of the first and second refrigerant medium branches.
 5. The heat pump circuit according to claim 4, wherein the heat pump circuit includes a second heat exchanger arranged in the first refrigerant medium branch, the second heat exchanger being configured to permit flow of air through the second heat exchanger.
 6. The heat pump circuit according to claim 5, wherein the electric heater device is arranged in the second refrigerant medium branch.
 7. The heat pump circuit according to claim 6, wherein the second refrigerant medium branch has a refrigerant medium tube through which refrigerant medium flows, the refrigerant medium tube being arranged to be heated by the electric heater device.
 8. The heat pump circuit according to claim 7, wherein at least one expansion element is arranged downstream in the direction of flow of the refrigerant medium from the first heat exchanger and upstream of the second heat exchanger and the electric heater device.
 9. The heat pump circuit according to claim 8, wherein a first expansion element of the at least one expansion element is arranged in the first refrigerant medium branch upstream of the second heat exchanger.
 10. The heat pump circuit according to claim 9, wherein a second expansion element of the at least one expansion element is arranged in the second refrigerant medium branch upstream of the electric heater device.
 11. The heat pump circuit according to claim 10, wherein at least one shut-off device is included in at least one of the first refrigerant medium branch and the second refrigerant medium branch, the at least one shut-off device being configured to permit selective shut-off of refrigerant medium flow.
 12. A heat pump circuit according to claim 11, wherein air does not directly flow around or through components of the second refrigerant medium branch. 